Taper roller bearing

ABSTRACT

A taper roller bearing includes: an inner ring, an outer ring, a plurality of taper rollers, and an annular cage. The cage includes a small-diameter annular portion on one axial side, a large-diameter annular portion on the other axial side, and a plurality of column portions. A radial inner surface of the column portion is provided along a second virtual taper surface that is in the vicinity of a first virtual taper surface including a center line of the plurality of taper rollers, across the entire length in the longitudinal direction of the column portion.

This application is a National Stage of International ApplicationPCT/JP2015/079918 filed Oct. 23, 2015, which is based upon and claimsthe benefit of priority from Japanese Patent Application No. 2014-220293filed Oct. 29, 2014, the entire contents of the prior applications beingincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a taper roller bearing.

BACKGROUND ART

A taper roller bearing has a larger load capacity compared to anotherrolling bearing having the same size and has high rigidity.

FIG. 19 is a longitudinal sectional view illustrating a taper rollerbearing 100 of the related art. The taper roller bearing 100 includes aninner ring 101, an outer ring 102, a plurality of taper rollers 103which are provided between the inner ring 101 and the outer ring 102,and an annular cage 104 which holds the taper rollers 103 at an intervalin the circumferential direction (for example, refer to Patent Document1).

The cage 104 includes a small-diameter annular portion 105 on one axialside, a large-diameter annular portion 106 on the other axial side, anda plurality of column portions 107 which link the annular portions 105and 106 to each other. In addition, a space formed between both of theannular portions 105 and 106 and between the column portions 107 and 107adjacent to each other in the circumferential direction is a pocket 108which accommodates the taper roller 103 therein.

In addition, in the taper roller bearing 100, a diameter of an innercircumferential surface of the outer ring 102 widens as approaching theother side from one axial side, and when the taper roller bearing 100(for example, inner ring 101) rotates, an action (pump action) by whichthe lubricating oil flows from one axial side to the other side betweenthe outer ring 102 and the inner ring 101 is generated. It is knownthat, by the pump action which follows the rotation of the taper rollerbearing 100, the lubricating oil on the outside of the bearing flows tothe inside of the bearing from one axial side, and flows out from theother axial side.

PRIOR ART DOCUMENTS Patent Document

[Patent Document 1] JP-B-4151347

SUMMARY OF INVENTION Technical Problem

In general, rotation torque of the taper roller bearing tends toincrease compared to that of a ball bearing. Torque loss of the taperroller bearing is mainly broadly classified into three including rollingviscosity resistance between raceway rings (the inner ring 101 and theouter ring 102) and the taper roller 103, agitating resistance of thelubricating oil on the inside of the bearing, and sliding frictionresistance between the taper roller 103 and a large flange 101 bincluded in the inner ring 101.

Among these, the rolling viscosity resistance and the agitatingresistance take most part of the torque loss particularly during therotation at a high speed, and becomes a main reason of an increase inrotation torque.

In addition, the rolling viscosity resistance and the agitatingresistance depend on the amount of lubricating oil which flows to theinside of the bearing, and it is possible to reduce the torque loss bysuppressing the amount of inflow of the lubricating oil which flows tothe inside of the bearing.

Here, an object of the present invention is to provide a taper rollerbearing which can reduce rolling viscosity resistance and agitatingresistance by the lubricating oil on the inside of the bearing.

Solution to Problem

According to the present invention, a taper roller bearing includes: aninner ring which includes a small flange that is positioned on one sidein an axial direction and protrudes to an outer side in a radialdirection, and a large flange that is positioned on the other axial sideand protrudes to the outer side in the radial direction; an outer ringwhich is positioned on the outer side in the radial direction of theinner ring; a plurality of taper rollers which are positioned betweenthe inner ring and the outer ring; and an annular cage which holds theplurality of taper rollers at an interval in the circumferentialdirection, in which the cage includes a small-diameter annular portionwhich is positioned on one side, a large-diameter annular portion whichis positioned on the other side, and a plurality of column portionswhich link the small-diameter annular portion and the large-diameterannular portion to each other, and in which an inner surface in theradial direction of each of the column portions is positioned along asecond virtual taper surface which is in the vicinity of a first virtualtaper surface including center lines of the plurality of taper rollersor which fits the first virtual taper surface, across an entire lengthin a longitudinal direction of the column portions.

Grooves may be formed on the inner surface in the radial direction ofthe column portions, each of the grooves extending along thelongitudinal direction of each of the column portions and being open onthe other side, and an extending virtual line which extends from an endportion on an opening side of bottom portion of each of the grooves mayintersect with a flange surface on the inner side in the axial directionof the large flange portion.

A diameter of the second virtual taper surface may be slightly smallerthan a diameter of the first virtual taper surface.

Each of the grooves preferably has a part which shallows as approachingan end of each of the grooves on the other side has a part which becomesshallow as approaching a final end of the groove on the other side.

The cage may include a slide contact surface which is slidably contactwith an inner circumferential surface of the outer ring so as toposition with respect to the radial direction of the cage.

Advantageous Effects of Invention

According to the present invention, when the taper roller bearingrotates, the radial inner surface of the column portion can scrape thelubricating oil attached to the outer circumferential surface of thetaper roller across the entire length in the longitudinal direction ofthe column portion. As a result, it is possible to reduce rollingviscosity resistance and agitating resistance.

According to the present invention, it is possible to supply thelubricating oil scraped by the radial inner surface of the columnportion to the flange surface of the large flange along the groove, andto reduce the sliding friction resistance between the large flangeportion and the taper roller by the lubricating oil.

According to the present invention, the radial inner surface of thecolumn portion is configured to be provided along the second virtualtaper surface which is slightly smaller than the first virtual tapersurface including the center line of the plurality of taper rollers.

Here, the groove is formed on the radial inner surface of the columnportion, but rigidity (strength) of the radial inner end portion of thecolumn portion deteriorates by the groove compared to other parts.

However, as the diameter of the second virtual taper surface is slightlysmaller than that of the first virtual taper surface, as describedabove, a configuration in which the radial inner end portion of thecolumn portion having low rigidity (strength) does not come into contactwith the taper roller and hold the taper roller, and the other part (apart at which influence of the groove is weak) comes into contact withthe taper roller and holds the taper roller, is obtained.

According to the present invention, since the groove has a part whichbecomes shallow as approaching the final end of the groove on the otherside, it is possible to flow the lubricating oil that flows along thegroove to the flange surface of the large flange while having a speedcomponent in the flow direction, and to efficiently supply thelubricating oil to the flange surface.

According to the present invention, since the cage has the slide contactsurface, in the taper roller bearing in which the cage is guided by theouter ring, it is possible to reduce rolling viscosity resistance andagitating resistance.

According to the present invention, it is possible to scrape thelubricating oil attached to the outer circumferential surface of thetaper roller by the radial inner surface of the column portion, and toreduce rolling viscosity resistance and agitating resistance.Accordingly, it is possible to reduce energy loss in an apparatus inwhich the taper roller bearing is used.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal sectional view illustrating an embodiment of ataper roller bearing.

FIG. 2 is a perspective view of a cage.

FIG. 3 is a sectional view describing a small-diameter annular portionand the periphery thereof.

FIGS. 4(A) and 4(B) are views describing a shape of a fine clearance.

FIG. 5 is a sectional view of an inner ring, an outer ring, and thecage.

FIG. 6 is a sectional view in which the inner ring, the outer ring, thecage, and a taper roller are viewed from the axial direction.

FIG. 7 is a sectional view illustrating that a part of the inner ringand the cage is enlarged.

FIG. 8 is a perspective view illustrating a large-diameter annularportion and the periphery thereof.

FIGS. 9(A) and 9(B) are views describing forming of the fine clearance.

FIG. 10 is a sectional view illustrating a large flange, alarge-diameter annular portion, and the periphery thereof.

FIG. 11 is a sectional view illustrating the large flange, thelarge-diameter annular portion, and the taper roller.

FIG. 12 is a perspective view in which a part of the cage illustrated inFIG. 2 is viewed from an inner circumferential side.

FIG. 13(A) to FIG. 13(C) are views describing an order of assembly ofthe taper roller bearing.

FIG. 14 is a perspective view of the cage and the taper roller.

FIG. 15 is a longitudinal sectional view of a half-split mold and thecage.

FIG. 16 is a front view of a part of the cage viewed from one axialside.

FIG. 17 is a rear view of a part of the cage viewed from the other axialside.

FIG. 18 is a perspective view of the cage in a case where a columnportion is provided to be long in the radial direction.

FIG. 19 is a longitudinal sectional view illustrating a taper rollerbearing of the related art.

DESCRIPTION OF EMBODIMENTS

[Entire Configuration of Taper Roller Bearing]

FIG. 1 is a longitudinal sectional view illustrating an embodiment of ataper roller bearing 1. The taper roller bearing 1 includes an innerring 2, an outer ring 3 which is provided on a radial outer side of theinner ring 2, a plurality of taper rollers 4 which are provided betweenthe inner ring 2 and the outer ring 3, and an annular cage 10 whichholds the taper rollers 4. In addition, the taper roller bearing 1 islubricated by lubricating oil (oil).

The inner ring 2 is an annular member which is formed by using bearingsteel or steel for a mechanical structure, and a tapered inner ringraceway surface 2 a on which the plurality of taper rollers 4 roll isformed on an outer circumference of the inner ring 2. In addition, theinner ring 2 includes a small flange 5 which protrudes to the radialouter side provided on one axial side (left side in FIG. 1) of the innerring raceway surface 2 a, and a large flange 6 which protrudes to theradial outer side provided on the other axial side (right side inFIG. 1) of the inner ring raceway surface 2 a.

Similar to the inner ring 2, the outer ring 3 is also an annular memberformed by using bearing steel or steel for a mechanical structure, and atapered outer ring raceway surface 3 a which opposes the inner ringraceway surface 2 a and on which the plurality of taper rollers 4 rollis formed on an inner circumference of the outer ring 3. The racewaysurfaces 2 a and 3 a are super-finished (finishing processing).

The taper roller 4 is a member formed by using bearing steel, and rollson the inner ring raceway surface 2 a and on the outer ring racewaysurface 3 a. The taper roller 4 includes a small end surface 4 a havinga small diameter on one axial side, and a large end surface 4 b having alarge diameter on the other axial side. The large end surface 4 b issuper-finished (finishing processing) after slidably coming into contactwith a flange surface 7 of the large flange 6. In addition, the flangesurface 7 is also super-finished (finishing processing).

FIG. 2 is a perspective view of the cage 10. In FIGS. 1 and 2, the cage10 includes a small-diameter annular portion 11 on one axial side, alarge-diameter annular portion 12 on the other axial side, and aplurality of column portions 13. The small-diameter annular portion 11and the large-diameter annular portion 12 are annular, and are providedto be separated at a predetermined interval in the axial direction. Thecolumn portion 13 is provided at an interval in the circumferentialdirection, and links the annular portions 11 and 12. A space which isformed between the two column portions 13 and 13 adjacent to each otherin the circumferential direction, that is, between both of the annularportions 11 and 12 is a pocket 14 which accommodates (holds) the taperroller 4 therein. The cage 10 of the embodiment is made of a resin (madeof a synthetic resin) formed by injection molding that uses a half-splitmold (51 and 52, refer to FIG. 15) that will be described later, and forexample, the cage 10 can be made of a polyphenylene sulfide resin (PPS)or the like, and can be made of a fiber-reinforced resin (FRP).

In FIG. 1, the cage 10 is provided in an annular space S (hereinafter,also referred to as the inside of a bearing) which is formed between theinner ring 2 and the outer ring 3, accommodates one taper roller 4 ineach pocket 14, and holds the plurality of taper rollers 4 beingdisposed at an equivalent interval in the circumferential direction. Inaddition, the small-diameter annular portion 11 is positioned on theradial outer side of the small flange 5 of the inner ring 2, and thelarge-diameter annular portion 12 is positioned on the radial outer sideof the large flange 6 of the inner ring 2.

In FIG. 1, in the cage 10, axial inner surfaces 11 c and 12 c which facethe pocket 14 side of both of the annular portions 11 and 12 can comeinto contact with the small end surface 4 a and the large end surface 4b of the taper roller 4 (refer to FIG. 1), and accordingly, the axialmovement of the cage 10 is regulated. In the embodiment, in particular,the axial movement of the cage 10 is regulated as the axial innersurface 12 c comes into contact with the large end surface 4 b. In otherwords, the cage 10 is positioned with respect to the axial direction asthe annular portions 11 and 12 come into contact with the taper roller4. Since the finishing processing, such as polishing, is performed withrespect to the large end surface 4 b and accuracy is high, the cage 10is positioned with high accuracy.

In addition, the cage 10 is positioned with respect to the radialdirection as a part thereof (slide contact surfaces 40 and 39) slidablycomes into contact with an inner circumferential surface 3 b of theouter ring 3. A configuration for this will be described. In FIG. 2, thecage 10 includes a first roller retaining portion 41 and a second rollerretaining portion 42 which are formed to be integrated with the columnportion 13. A part (part on the small-diameter annular portion 11 side)of the radial outer surface of the column portion 13 and the radialouter surface of the first roller retaining portion 41 are smoothlycontinuous arc surfaces. In addition, the other part (part on thelarge-diameter annular portion 12 side) of the radial outer surface ofthe column portion 13 and the radial outer surface of the second rollerretaining portion 42 are smoothly continuous arc surfaces. The arcsurfaces have a shape along a virtual taper surface having a diameterwhich is slightly smaller than that of the inner circumferential surface3 b of the outer ring 3, and the arc surfaces are the slide contactsurfaces 40 and 39 which can slidably come into contact with the innercircumferential surface 3 b of the outer ring 3. The slide contactsurfaces 40 and 39 are positioned with respect to the radial directionof the cage 10 by slidably coming into contact with the innercircumferential surface 3 b of the outer ring 3. In addition, the shapeand other functions of the roller retaining portions 41 and 42 will bedescribed later. In addition, in the slide contact surface 40, a part ofan outer circumferential surface 11 a of the small-diameter annularportion 11 is also included.

In FIG. 1, in the taper roller bearing 1, a diameter of the innercircumferential surface 3 b of the outer ring 3 is enlarged from oneaxial side to the other side. Therefore, when the taper roller bearing 1(inner ring 2 in the embodiment) rotates, an action (pump action) bywhich the lubricating oil flows from one axial side to the other side inthe annular space S formed between the inner ring 2 and the outer ring 3is generated. By the pump action which follows the rotation of the taperroller bearing 1, the lubricating oil on the outside of the bearingflows into the annular space S (inside of the bearing) between the innerring 2 and the outer ring 3 from one axial side, and flows out from theother axial side. In other words, the lubricating oil passes through theinside of the bearing. Above, in the taper roller bearing 1 illustratedin FIG. 1, one axial side becomes an inflow side of the lubricating oil,and the other axial side becomes an outflow side of the lubricating oil.

[Regarding Small-Diameter Annular Portion 11 of Cage 10]

FIG. 3 is a sectional view describing the small-diameter annular portion11 and the periphery thereof. On an outer circumferential side of thesmall-diameter annular portion 11, an angle portion 58 in which theouter circumferential surface 11 a and the axial inner surface 11 c ofthe small-diameter annular portion 11 intersect with each other isformed. In addition, an angle portion (angle portion having a small R)59 in which a side surface 3 c and an inner circumferential surface 3 bof the outer ring 3 intersect with each other is formed. A tip end ofthe angle portion 58 of the small-diameter annular portion 11 is in thevicinity of the angle portion 59 of the outer ring 3, and is positionedfurther on the inside of the bearing than the angle portion 59 of theouter ring 3. Accordingly, an annular fine clearance K1 is formedbetween the small-diameter annular portion 11 and an end portion 3 d ofthe outer ring 3.

On the inner circumferential side of the small-diameter annular portion11, an inner circumferential surface 11 b of the small-diameter annularportion 11 opposes an outer circumferential surface 5 a of the smallflange 5 of the inner ring 2 in the radial direction, the innercircumferential surface 11 b and the outer circumferential surface 5 aare close to each other, and an annular fine clearance K2 is formedtherebetween.

Above, an annular opening portion A1 is formed between the small flange5 of the inner ring 2 and the end portion 3 d on one axial side of theouter ring 3, and the small-diameter annular portion 11 is configured toblock the annular opening portion A1 at the fine clearances K1 and K2between each of the small flange 5 and the end portion 3 d of the outerring 3.

For example, in a case where the inner diameter of the taper rollerbearing 1 is 30 to 40 mm and the outer diameter is 70 to 80 mm, the fineclearance K1 on the radial outer side can be 50 to 125 μm, and is 100 μmin the embodiment. In addition, in the taper roller bearing 1 having thedimension, the fine clearance K2 on the radial inner side can be 50 to125 μm, and is 100 μm in the embodiment. In addition, in the embodiment,a radial dimension partially changes in each of the fine clearances K1and K2, but the value is a radial dimension, and the clearance is adimension at a part at which the clearance is the minimum.

As illustrated in the enlarged view on the inner ring 2 side of FIG. 3,in the embodiment, the inner circumferential surface 11 b of thesmall-diameter annular portion 11 includes a first inner circumferentialsurface portion 21 which is positioned on the inside of the bearing, anda second inner circumferential surface portion 22 which is positioned onthe outside of the bearing. The first inner circumferential surfaceportion 21 and the second inner circumferential surface portion 22 arecylindrical surfaces around a center line C0 (refer to FIG. 1) of thetaper roller bearing 1, and a diameter D2 of the second innercircumferential surface portion 22 is smaller than a diameter D1 of thefirst inner circumferential surface portion 21 (D2<D1). The innercircumferential surface portions 21 and 22 are continuous to each othervia an annular surface 23.

The outer circumferential surface 5 a of the small flange 5 whichradially opposes the inner circumferential surface 11 b of thesmall-diameter annular portion 11 includes a first outer circumferentialsurface portion 24 which opposes the first inner circumferential surfaceportion 21 with a fine clearance K2-1, and a second outercircumferential surface portion 25 which opposes the second innercircumferential surface portion 22 with a fine clearance K2-2. The firstouter circumferential surface portion 24 has a cylindrical surfacearound the center line C0 of the taper roller bearing 1, and the secondouter circumferential surface portion 25 has an R-surface which isformed in the small flange 5. The first outer circumferential surfaceportion 24 and the second outer circumferential surface portion 25 arecontinuous to each other, and a boundary thereof is a virtual surfacewhich is orthogonal to the center line C0 including the annular surface23. In addition, a diameter d2 of the second outer circumferentialsurface portion 25 is smaller than a diameter d1 of the first outercircumferential surface portion 24 (d2<d1).

According to the configuration in the small-diameter annular portion 11,the annular opening portion A1 which is the inflow side of thelubricating oil can suppress the inflow of the lubricating oil to theinside of the bearing being blocked by the small-diameter annularportion 11 of the cage 10 with the fine clearances K1 and K2.Furthermore, a labyrinth structure having the annular fine clearancesK2-1 and K2-2 which have different steps (different diameters) is formedbetween the small flange 5 and the small-diameter annular portion 11,and on the inner ring 2 side of the annular opening portion A1, it ispossible to more efficiently suppress the inflow of the lubricating oilto the inside of the bearing. As a result, as an amount of lubricatingoil decreases on the inside of the bearing, it is possible to reducerolling viscosity resistance and agitating resistance of the taperroller bearing 1, and a rotation torque of the taper roller bearing 1 isreduced.

In addition, the lubricating oil which passes through the fineclearances K1 and K2 is used for lubricating the taper roller bearing 1.In other words, the fine clearances K1 and K2 allow passage of thelubricating oil, but the inflow of the lubricating oil of which anamount is equal to or greater than an amount necessary for thelubrication to the inside of the bearing is restricted on the inside ofthe taper roller bearing 1.

In addition, in the embodiment, the diameter d1 of the first outercircumferential surface portion 24 is greater than the diameter D2 ofthe second inner circumferential surface portion 22 (d1>D2), the fineclearance K2-1 is configured not be seen from one axial side, and it ispossible to more efficiently suppress intrusion of the lubricating oil.

As illustrated in FIG. 1, the inner ring 2 of the taper roller bearing 1is externally fitted and attached to a shaft (rotation shaft) 8, and acircular portion 9 is provided on one axial side. The circular portion 9may be an annular member which is externally fitted and attached to theshaft (rotation shaft) 8, or may be a part (part of which the diameteris large) of the shaft 8.

In this case, the diameter D2 of the second inner circumferentialsurface portion 22 of which the diameter is the minimum on the innercircumferential surface 11 b of the small-diameter annular portion 11(refer to FIG. 3) is set to be greater than an outer diameter d7 of thecircular portion 9 (D2>d7). In addition, the maximum value of the outerdiameter d7 is determined according to an ISO (InternationalOrganization for Standardization) standard. In other words, in theembodiment, the diameter D2 of the second inner circumferential surfaceportion 22 is set to be greater than a value based on the ISO value thatis the outer diameter d7 of the circular portion 9.

Here, the outer diameter d7 (maximum value) of the circular portion 9 isdetermined in accordance with the size of the taper roller bearing 1.For example, in a case where the inner diameter is 30 mm, the outerdiameter is 55 mm, and an axial dimension (entire width) is 17 mm, themaximum value of the outer diameter d7 of the circular portion 9 basedon the ISO standard is 35 mm. In this case, the diameter D2 of thesecond inner circumferential surface portion 22 is set to be greaterthan the outer diameter d7 (35 mm). For example, in a case where thediameter D2 of the second inner circumferential surface portion 22 canbe set to be greater than the outer diameter d7 by 1 to 3 millimeters,and the outer diameter d7 of the circular portion 9 is 35 mm, thediameter D2 of the second inner circumferential surface portion 22 canbe, for example, 37 mm.

By setting an inner circumferential surface shape of the small-diameterannular portion 11 in this manner, while maintaining the shape of thebearing based on the ISO standard, the taper roller bearing 1 can beprovided with the labyrinth structure on the small flange 5 side of theinner ring 2.

In addition, as described above, in order to provide the fine clearanceK2 (K2-1 and K2-2) having high dimension accuracy between the smallflange 5 and the small-diameter annular portion 11, the finishingprocessing, such as polishing, is performed with respect to the outercircumferential surface 5 a of the small flange 5, and additionally, thecage 10 made of a resin may be molded with high accuracy using a mold.

Otherwise, as another means for providing the fine clearance K2 (K2-1and K2-2) having high dimension accuracy, the taper roller bearing 1having the following configuration may be employed.

In other words, a point that the cage 10 made of a resin is molded usinga mold is the same, but as illustrated in FIG. 4(A), a radial clearanceK0 between the small flange 5 and the small-diameter annular portion 11is set to be a negative clearance. In addition, in FIG. 4(A), thesmall-diameter annular portion 11 (inner circumferential surface 11 b)is illustrated by a two-dot chain line. In other words, a diameter d ofthe outer circumferential surface 5 a of the small flange 5 is slightlygreater than a diameter D of the inner circumferential surface 11 b ofthe small-diameter annular portion 11 (d>D).

Here, when the taper roller bearing 1 (refer to FIG. 1) rotates, thetaper roller 4 rolls on the inner ring raceway surface 2 a of the innerring 2 and on the outer ring raceway surface 3 a of the outer ring 3,and accordingly, the cage 10 also rotates with respect to the inner ring2 and the outer ring 3. Here, as initial compatibility processing,processing of rotating the taper roller bearing 1 for a predeterminedperiod of time after assembly is performed.

In other words, as described above, since the radial clearance K0between the small flange 5 and the small-diameter annular portion 11 isset to be a negative clearance, as illustrated in FIG. 4(B), thesmall-diameter annular portion 11 (a part of the inner circumferentialsurface 11 b) is worn out slidably moving therebetween, and between thesmall flange 5 and the small-diameter annular portion 11, the minimumfine clearance K2 (positive clearance) is automatically formed. This isbecause the inner ring 2 is made of steel while the cage 10 is made of aresin, and the small-diameter annular portion 11 is made of a materialhaving lower wear resistance than that of the small flange 5.

Accordingly, it is possible form (automatically form) the labyrinthstructure between the small flange 5 and the small-diameter annularportion 11 that is a on the inflow side of the lubricating oil.

In addition, in the aspect illustrated in FIGS. 4(A) and 4(B), a casewhere the radial clearance K0 between the small flange 5 and thesmall-diameter annular portion 11 is a negative clearance is described,but the radial clearance K0 may be a zero clearance. In other words,when describing with reference to FIG. 4(A), the diameter d of the outercircumferential surface 5 a of the small flange 5 may be the same as thediameter D of the inner circumferential surface 11 b of thesmall-diameter annular portion 11 (d=D). In this case, the fineclearance K2 (positive clearance) is also automatically formed.

In addition, as described in FIGS. 4(A) and 4(B), since the fineclearance K2 is automatically formed, it is preferable that the outercircumferential surface 5 a of the small flange 5 is a coarse surface,and accordingly, it is possible to promote the wear of thesmall-diameter annular portion 11 by the slidable movement. In addition,since the outer circumferential surface 5 a of the small flange 5 is acoarse surface, for example, the outer circumferential surface 5 a canbe a cutting surface to which cutting processing is performed, or can bea corrugated surface to which blast processing (shot blasting).

[Regarding Column Portion 13 of Cage 10]

FIG. 5 is a longitudinal sectional view of the inner ring 2, the outerring 3, and the cage 10. FIG. 6 is a sectional view when the inner ring2, the outer ring 3, the cage 10, and the taper roller 4 are viewed fromthe axial direction. In addition, in FIG. 6, in order to describe theshape of the column portion 13 (groove 18 which will be describedlater), the shape is deformed to be different from a real shape in thedescription.

Here, in FIG. 1, since the plurality of taper rollers 4 held by the cage10 are installed along the inner ring raceway surface 2 a and the outerring raceway surface 3 a which have a tapered shape, each of centerlines C1 of the taper rollers 4 is included on single virtual tapersurface J1 (first virtual taper surface) of which a diameter increasesas approaching from one axial side to the other side.

In addition, in the embodiment, as illustrated in FIGS. 5 and 6, aradial inner surface 17 of the column portion 13 is provided along asecond virtual taper surface J2 set in the vicinity of the first virtualtaper surface J1 across the entire length of the column portion 13 inthe longitudinal direction. The second virtual taper surface J2 has ashape of which a diameter increases as approaching from one axial sideto the other side. In addition, the first virtual taper surface J1 andthe second virtual taper surface J2 may be in a similarity relation, butmay not be in a similarity relation.

The second virtual taper surface J2 of the embodiment has a diameterwhich is slightly smaller than that of the first virtual taper surfaceJ1. Therefore, the radial inner surface 17 of the column portion 13 isconfigured to be provided along the second virtual taper surface J2which is slightly smaller than the first virtual taper surface J1, andthe radial inner surface 17 is positioned further on the radial innerside than a half portion on the outer ring 3 side in the taper roller 4.A radius difference between the first virtual taper surface J1 and thesecond virtual taper surface J2 can be, for example, in a range of 500μm to 1000 μm including the maximum value and the minimum value thereof,and the radius difference (minimum value) in the embodiment is 700 μm.

In addition, in the radial inner surface 17, the groove 18 which extendsalong the longitudinal direction of the column portion 13 is formed. Asillustrated in FIG. 5, the groove 18 has a surface (groove side surface18 a) which intersects with (is orthogonal to) the groove longitudinaldirection on one axial side, and is not open on one axial side.

Meanwhile, the groove 18 does not have a surface which is orthogonal tothe groove longitudinal direction on the other axial side, and is openon the other axial side. Specifically speaking, the groove 18 has ashallow part 18 e (refer to FIGS. 7 and 8) as approaching a groove finalend (end portion 18 d) on the other axial side in a region on the otheraxial side from a middle portion 18 b, and as the groove depth becomeszero at the groove final end (end portion 18 d), the groove 18 isconfigured to be open as approaching the other radial side.

Therefore, a sectional shape of the groove 18 is not constant along thegroove longitudinal direction and changes in the middle portion 18 b onthe other axial side. In a region on the other axial side from themiddle portion 18 b, as the groove 18 becomes shallow, the groovesectional shape becomes smaller. In addition, as illustrated in FIG. 7,an extending virtual line J3 which extends from the end portion (groovefinal end) 18 d on the opening side of a bottom portion 18 c intersectswith the flange surface 7 on the axial inner side of the large flange 6.

According to the configuration in the radial inner surface 17 of thecolumn portion 13, when the taper roller bearing 1 rotates, the taperroller 4 rotates around the center line C1 of itself, and the radialinner surface 17 can scrap the lubricating oil attached to an outercircumferential surface 4 c of the taper roller 4 across the entirelength in the longitudinal direction of the column portion 13.Therefore, it is possible to reduce rolling viscosity resistance andagitating resistance in the taper roller bearing 1.

Furthermore, in the embodiment, as illustrated in FIG. 5, since theradial inner surface 17 is inclined to the radial outer side asapproaching the other axial side, the scraped lubricating oil flows tothe other axial side along the radial inner surface 17 by a centrifugalforce. Here, since the groove 18 is provided on the radial inner surface17, the lubricating oil can flow along the groove 18 not being attachedto the taper roller 4 again, and is supplied to the flange surface 7 ofthe large flange 6. Therefore, it is possible to reduce sliding frictionresistance between the large flange 6 and the taper roller 4 by thesupplied lubricating oil.

In addition, as described above, the groove 18 has a part 18 e (refer toFIGS. 7 and 8) which becomes shallow as approaching the groove final end(end portion 18 d) on the other axial side in a region on the otheraxial side from the middle portion 18 b. Accordingly, the lubricatingoil which flows along the groove 18 can flow toward the flange surface 7of the large flange 6 while having a speed component in the flowdirection, and it is possible to efficiently supply the lubricating oilto the flange surface.

In addition, the first virtual taper surface J1 and the second virtualtaper surface J2 may match each other. In this case, the radial innersurface 17 can also scrape the lubricating oil attached to the outercircumferential surface 4 c of the taper roller 4.

However, as described in the embodiment illustrated in FIGS. 5 and 6, itis preferable that the second virtual taper surface J2 has a diameterwhich is slightly smaller than that of the first virtual taper surfaceJ1 across the entire length in the axial direction.

The reason thereof is that the rigidity (strength) of a radial inner endportion 13 a (refer to FIG. 6) of the column portion 13 becomes lowercompared to that of the other part (solid part 13 b further on theradial outer side than the radial inner end portion 13 a) by the groove18 in a case where the groove 18 is formed on the radial inner surface17 of the column portion 13. In other words, this is because aconfiguration in which, since the taper roller 4 comes into contact withthe column portion 13 at a part at which the first virtual taper surfaceJ2 intersects with the circumferential side surface 13 c of the columnportion 13, the diameter of the second virtual taper surface J2 isslightly smaller than the diameter of the first virtual taper surfaceJ1, and thus, as described above, the radial inner end portion 13 ahaving low rigidity (strength) does not hold the taper roller 4 cominginto contact with the taper roller 4, but the other part (part at whichthe influence of the groove 18 becomes weak: solid part 13 b) holds thetaper roller 4 coming into contact with the taper roller 4, is employed.

Above, in the embodiment, the taper roller 4 can come into contact withthe solid part 13 b at which the groove 18 in the column portion 13 isnot provided, and it is prevented that the groove 18 becomes a weaknessfrom the viewpoint of a strength. In addition, as illustrated in FIG. 6,the circumferential side surface (pocket surface) 13 c in the columnportion 13 (excluding the roller retaining portion 41 which will bedescribed later) becomes a surface which is in a linear shape along theradial direction.

As described above, in the embodiment, the minimum value of the radiusdifference between the first virtual taper surface J1 and the secondvirtual taper surface J2 is 700 μm. This is based on the shape of thegroove 18 which is a semicircular shape and the radius thereof which is500 μm in FIG. 6. In addition, in this case, a groove width which is thecircumferential dimension of the groove 18 is 1 mm. In other words,since the taper roller 4 is brought into contact with the solid part 13b of the column portion 13, it is necessary that the minimum value ofthe radius difference between the first virtual taper surface J1 and thesecond virtual taper surface J2 is a value obtained by adding a margindimension to the depth (radius) of the groove 18. In the embodiment, avalue (700 μm) obtained by adding 200 μm as a margin dimension to 500 μmof the depth (radius) of the groove 18 is the minimum value of theradius difference.

A shape on the radial outer side of the column portion 13 will bedescribed. In FIG. 2, on the radial outer side of the column portion 13,a recess portion 33 which allows the pockets 14 and 14 adjacent to eachother to communicate with each other by being recessed in the radialdirection is provided. In addition, in the recess portion 33, a depth ofan end 33 a (refer to FIG. 5) on one axial side is zero and a bottomsurface 33 b of the recess portion 33 has a shape of an inclined surfacethat is inclined as approaching the radial outer side toward the otheraxial side. In this manner, as the recess portions 33 are provided ineach of the column portion 13, the lubricating oil in the vicinity ofthe inner circumferential surface 3 b of the outer ring 3 can flowbetween the pockets 14 and 14 adjacent to each other, and can weaken theagitating resistance of the lubricating oil.

[Regarding Large-Diameter Annular Portion 12 of Cage 10 (First Thereof)]

As described above, in the taper roller bearing 1 illustrated in FIG. 1,one axial side is an inflow side of the lubricating oil and the otheraxial side is an outflow side of the lubricating oil. In other words,the lubricating oil flows out from an annular opening portion A2 formedbetween the large flange 6 of the inner ring 2 and an end portion 3 e onthe other axial side of the outer ring 3. In addition, thelarge-diameter annular portion 12 is provided in the annular openingportion A2.

FIG. 8 is a perspective view illustrating the large-diameter annularportion 12 and the periphery thereof. A configuration on the outer ring3 side of the large-diameter annular portion 12, that is, on the outercircumferential side of the large-diameter annular portion 12 will bedescribed first.

A cut-out portion 15 which is continuous to the pocket 14 is provided onthe outer circumferential side of the large-diameter annular portion 12.As illustrated in FIG. 3, while the annular opening portion A1 on theinflow side of the lubricating oil is blocked having the fine clearancesK1 and K2 by the small-diameter annular portion 11, the annular openingportion A2 (refer to FIG. 8) which is the outflow side of thelubricating oil is provided with the cut-out portion 15, and accordingto this, the annular opening portion A2 is not blocked and the pocket 14is open on the radial outer side of the large-diameter annular portion12. By the cut-out portion 15, on the outflow side (annular openingportion A2) of the lubricating oil, it is possible to promote thedischarge of the lubricating oil on the inside of the bearing, and toreduce rolling viscosity resistance and agitating resistance in thetaper roller bearing 1.

Next, a configuration on an inner circumferential side of thelarge-diameter annular portion 12 will be described. In FIG. 8, an innercircumferential surface 12 a of the large-diameter annular portion 12opposes an outer circumferential surface 6 a of the large flange 6 inthe radial direction, the inner circumferential surface 12 a and theouter circumferential surface 6 a approach each other, and an annularfine clearance K3 is formed therebetween.

For example, in a case where the inner diameter of the taper rollerbearing 1 is 30 to 40 mm and the outer diameter is 70 to 80 mm, the fineclearance K3 can be 75 to 125 μm, and is 100 μm in the embodiment. Inaddition, the radial dimension of the fine clearance K3 may partiallychange, and the value is a dimension in the radial direction and is adimension at a part at which the clearance is the minimum.

In addition, the fine clearance K3 may be set to decrease as approachingthe other axial side (outside of the bearing), that is, toward theoutflow direction of the lubricating oil.

Above, the labyrinth structure which suppresses the flow of thelubricating oil to the outside of the bearing from the inside of thebearing is formed between the large flange 6 and the large-diameterannular portion 12. According to the labyrinth structure, the outflow ofthe lubricating oil from between the large flange 6 and thelarge-diameter annular portion 12 can be suppressed, the lubricating oilcan remain in the vicinity of the flange surface 7 of the large flange6. In particular, in the embodiment, in the region on the radial outerside of the flange surface 7 which is the upstream side of the fineclearance K3, an annular enlarged space portion K4 is formed, and thelubricating oil can remain in the annular enlarged space portion K4. Inaddition, the annular enlarged space portion K4 is made of a regionformed between the large flange 6 and the cage 10. In addition, it ispossible to use the lubricating oil which remains in the vicinity of theflange surface 7 as the lubricating oil for the lubrication between theflange surface 7 and the large end surface 4 b of the taper roller 4,and to reduce sliding friction resistance between the large flange 6 andthe taper roller 4.

In addition, as described above, since the cut-out portion 15 which iscontinuous to the pocket 14 is provided on the outer circumferentialside of the large-diameter annular portion 12, in the annular openingportion A2 which is the outflow side of the lubricating oil, on theouter ring 3 side, the discharge of the lubricating oil on the inside ofthe bearing is promoted. Meanwhile, on the inner ring 2 side, by thelabyrinth structure, it is possible to supply the lubricating oilbetween the flange surface 7 of the large flange 6 and the large endsurface 4 b of the taper roller 4.

Above, in order to reduce rolling viscosity resistance or agitatingresistance, it is possible to reduce the sliding friction resistance byholding the lubricating oil at a necessary part (slide surface betweenthe flange surface 7 and the large end surface 4 b) while promoting theoutflow of the lubricating oil on the inside of the bearing by thecut-out portion 15.

In addition, in the taper roller bearing 1 of the embodiment, asdescribed above, the small-diameter annular portion 11 of the cage 10blocks the annular opening portion A1 (refer to FIG. 3) on the inflowside of the lubricating oil having the fine clearances K1 and K2 betweeneach of the small flange 5 and the outer ring 3 (end portion 3 d).

In this manner, as the inflow side (annular opening portion A1) of thelubricating oil is blocked having the fine clearances K1 and K2 by thesmall-diameter annular portion 11, the inflow of the lubricating oil tothe inside of the bearing can be suppressed. Therefore, the amount ofoutflow increases in the annular opening portion A2 on the axialopposite side with respect to the inflow of the lubricating oil, andthere is a possibility that the inside of the bearing becomes a poorlubricating oil state. However, in FIG. 8, according to the labyrinthstructure formed between the large flange 6 and the large-diameterannular portion 12, it becomes possible to hold the minimum lubricatingoil which is necessary on the inside of the bearing, and the lubricatingoil can be used as the lubricating oil between the large flange 6 andthe taper roller 4.

Above, in order to reduce rolling viscosity resistance or agitatingresistance, it is possible to reduce the sliding friction resistance bygiving the lubricating oil at a necessary part while suppressing theinflow of the lubricating oil to the inside of the bearing by thesmall-diameter annular portion 11.

Here, as described above, since the fine clearance K3 having highdimension accuracy is provided between the large flange 6 of the innerring 2 and the large-diameter annular portion 12 of the cage 10, thefinishing processing, such as polishing, is performed with respect tothe outer circumferential surface 6 a of the large flange 6, and thecage 10 made of a resin may be molded using a mold with high accuracy.

In addition, as another means for providing the fine clearance K3 havinghigh dimension accuracy, the taper roller bearing 1 having the followingconfiguration may be employed.

In other words, a point that the cage 10 made of a resin is molded usinga mold is the same, but as illustrated in FIG. 9(A), a radial clearanceK10 between the large flange 6 and the large-diameter annular portion 12is set to be a negative clearance. In addition, in FIG. 9(A), thelarge-diameter annular portion 12 (inner circumferential surface 12 a)is illustrated by a two-dot chain line. In other words, a diameter da ofthe outer circumferential surface 6 a of the large flange 6 is greaterthan a diameter Da of the inner circumferential surface 12 a of thelarge-diameter annular portion 12 (da>Da).

In addition, similar to the technology described by using FIGS. 4(A) and4(B), when the taper roller bearing 1 (refer to FIG. 1) rotates, thecage 10 also rotates with respect to the inner ring 2 and the outer ring3, and thus, as the initial compatibility processing, processing ofrotating the taper roller bearing 1 for a predetermined period of timeafter the assembly is performed.

In other words, as described above, since the radial clearance K10between the large flange 6 and the large-diameter annular portion 12 isset to be a negative clearance, as illustrated in FIG. 9(B), thelarge-diameter annular portion 12 (inner circumferential surface 12 a)is worn out being slidable therebetween, and the minimum fine clearanceK3 (positive clearance) is automatically formed between the large flange6 and the large-diameter annular portion 12. This is because the innerring 2 is made of steel while the cage 10 is made of a resin, and thelarge-diameter annular portion 12 is made of a material having low wearresistance than that of the large flange 6.

Accordingly, it is possible to form (automatically form) the labyrinthstructure between the large flange 6 of the inner ring 2 which is theoutflow side of the lubricating oil and the large-diameter annularportion 12 of the cage 10.

In addition, in the embodiment illustrated in FIGS. 9(A) and 9(B), acase where the radial clearance K10 becomes a negative clearance isdescribed, but similar to the technology described by using FIGS. 4(A)and 4(B), the radial clearance K10 may be a zero clearance. Furthermore,similar to the technology described by using FIGS. 4(A) and 4(B), it ispreferable that the outer circumferential surface 6 a of the largeflange 6 is a coarse surface.

[Modification Example of Large-Diameter Annular Portion 12]

FIG. 10 is a sectional view illustrating the large flange 6, thelarge-diameter annular portion 12, and the periphery thereof. In theaspect illustrated in FIG. 10, the inner circumferential surface 12 a ofthe large-diameter annular portion 12 includes a first innercircumferential surface portion 26 which is positioned on the inside ofthe bearing, and a second inner circumferential surface portion 27 whichis positioned on the axial outer side. In addition, a diameter D4 of thesecond inner circumferential surface portion 27 is greater than adiameter D3 of the first inner circumferential surface portion 26(D4>D3). The inner circumferential surface portions 26 and 27 arecontinuous to each other via an annular surface 28.

The outer circumferential surface 6 a of the large flange 6 whichopposes the inner circumferential surface 12 a of the large-diameterannular portion 12 in the radial direction includes a first outercircumferential surface portion 29 which opposes the first innercircumferential surface portion 26 having a fine clearance K3-1, and asecond outer circumferential surface portion 30 which opposes the secondinner circumferential surface portion 27 having a fine clearance K3-2.In addition, a diameter d4 of the second outer circumferential surfaceportion 30 is greater than a diameter d3 of the first outercircumferential surface portion 29 (d4>d3).

According to the configuration in the above-described large-diameterannular portion 12, it is possible to form the labyrinth structurehaving clearances (K3-2 and K3-1) having different steps between thelarge flange 6 which is the outflow side of the lubricating oil and thelarge-diameter annular portion 12, and to improve a function ofsuppressing the outflow of the lubricating oil on the inside of thebearing. As a result, similar to the aspect illustrated in FIG. 8, it ispossible to allow the lubricating oil to remain in the vicinity of theflange surface 7 of the large flange 6. In addition, it is possible touse the lubricating oil which remains in the vicinity of the flangesurface 7 as the lubricating oil for the lubrication between the flangesurface 7 and the large end surface 4 b of the taper roller 4, and toreduce the sliding friction resistance between the large flange 6 andthe taper roller 4.

In addition, in the embodiment, the diameter d4 of the second outercircumferential surface portion 30 is greater than the diameter D3 ofthe first inner circumferential surface portion 26, the fine clearanceK3-2 is configured not to be seen from one axial side, and the outflowof the lubricating oil is more efficiently suppressed.

In the embodiment illustrated in FIG. 10, the large flange 6 includes anannular member 19 which is separated from the inner ring 2. Byexternally fitting and fixing the annular member 19 to the large flange6, the outer circumferential surface of the annular member 19 is thesecond outer circumferential surface portion 30. However, instead of theannular member 19, although not being illustrated, an annular portionhaving a sectional shape which is the same as that of the annular member19 may be formed in the large flange 6. In other words, the annularmember 19 may be molded to be integrated with the large flange 6.

[Regarding Large-Diameter Annular Portion 12 of Cage 10 (SecondThereof)]

FIG. 11 is a sectional view illustrating the large flange 6, thelarge-diameter annular portion 12, and the taper roller 4. At the centerof the large end surface 4 b of the taper roller 4, a cavity portion 16is formed. When manufacturing the taper roller 4, that is, whenpolishing the large end surface 4 b, the cavity portion 16 is necessary.The cavity portion 16 is made of a circular recess portion. In addition,in all of the taper rollers 4 included in one taper roller bearing 1,the cavity portions 16 having the same size are provided at the sameposition.

In addition, in the embodiment, the large-diameter annular portion 12and the large flange 6 cover the cavity portion 16 from the other axialside. In addition, the fine clearance K3 is formed between thelarge-diameter annular portion 12 and the large flange 6, and the fineclearance K3 has a function (labyrinth structure) of suppressing theoutflow of the lubricating oil as described above. Therefore, all of thecavity portions 16 are covered by the labyrinth structure made byforming the large-diameter annular portion 12, the large flange 6, andthe fine clearance K3.

A configuration of the large-diameter annular portion 12 for coveringall of the cavity portions 16 in this manner will be described.

Here, the plurality of taper rollers 4 are disposed along the inner ringraceway surface 2 a and the outer ring raceway surface 3 a, and arepositioned to abut against the flange surface 7. Therefore, asillustrated in the enlarged view of FIG. 11, it is possible to assume avirtual circle which links radial outer end portions 16 a of the cavityportions 16 of each of the taper roller 4. Here, in the embodiment, anouter diameter D5 of the axial inner surface 12 c included in thelarge-diameter annular portion 12 is configured to be greater than adiameter d5 of the virtual circle (D5>d5).

According to the configuration, on the outflow side of the lubricatingoil provided in the large-diameter annular portion 12, the axial innersurface 12 c of the large-diameter annular portion 12 can cover thecavity portion 16 (a large part thereof) of all of the taper rollers 4from the axial direction, and can hold the lubricating oil between theaxial inner surface 12 c and each of the cavity portions 16. Inaddition, it is possible to use the lubricating oil to be held as thelubricating oil between the flange surface 7 of the large flange 6 andthe large end surface 4 b of the taper roller 4, and thus, to reducesliding friction resistance between the large flange 6 and the taperroller 4.

In addition, as described above, on the outer circumferential side ofthe large-diameter annular portion 12, the cut-out portion 15 which iscontinuous to the pocket 14 is provided, and thus, it is possible topromote the discharge of the lubricating oil on the inside of thebearing on the outer ring 3 side in the annular opening portion A2 whichis the outflow side of the lubricating oil. Meanwhile, on the inner ring2 side, as described above, the large-diameter annular portion 12 cancover the cavity portion 16 of the large end surface 4 b of the taperroller 4 from the axial direction and can hold the lubricating oil.Accordingly, in order to reduce rolling viscosity resistance oragitating resistance, it is possible to reduce sliding frictionresistance by holding the lubricating oil at a necessary part (slidesurface between the flange surface 7 and the large end surface 4 b)while promoting the discharge of the lubricating oil on the inside ofthe bearing by the cut-out portion 15.

Furthermore, as described above, the labyrinth structure whichsuppresses the flow of the lubricating oil from the inside of thebearing to the outside of the bearing is provided between the largeflange 6 and the large-diameter annular portion 12. Therefore, it ispossible to suppress the outflow of the lubricating oil from the spacebetween the large flange 6 and the large-diameter annular portion 12,and to allow the lubricating oil to remain in the annular enlarged spaceportion K4 which is in the vicinity of the flange surface 7 of the largeflange 6. In particular, in the embodiment, as illustrated in FIG. 11,the cavity portion 16 is open with respect to the enlarged space portionK4 at the radial inner part. In other words, the cavity portion 16 andthe enlarged space portion K4 are linked to each other. Therefore, thelubricating oil held in the cavity portion 16 and the enlarged spaceportion K4 is supplied to the slide surface between the flange surface 7and the large end surface 4 b, and it is possible to use the lubricatingoil as the lubricating oil between the flange surface 7 and the largeend surface 4 b. As a result, it is possible to further more efficientlyreduce the sliding friction resistance of the slide surface.

[Regarding Roller Retaining Portions 41 and 42]

FIG. 12 is a perspective view in which a part of the cage 10 illustratedin FIG. 2 is viewed from an inner circumferential side. FIG. 13(A) toFIG. 13(C) are view describing an order of assembly of the taper rollerbearing 1. In FIG. 13(A), when assembling the taper roller bearing 1,first, the assembled cage 10 and the taper roller 4 are combined witheach other, and then, the combined cage 10 and taper roller 4 areassembled to the inner ring 2 (FIG. 13(C)). Here, when assembling thetaper roller bearing 1, it is necessary to prevent the taper roller 4accommodated in the pocket 14 from falling out to the radial outer side.Therefore, the cage 10 includes the first roller retaining portion 41and the second roller retaining portion 42. In addition, the assembly ofthe taper roller 4 to the cage 10 is performed by inserting the taperroller 4 into each of the pockets 14 from the inner circumferential sideof the cage 10.

In FIG. 12, the first roller retaining portions 41 are provided on thesmall-diameter annular portion 11 side, that is, on both sides in thecircumferential direction of each of the column portions 13. The firstroller retaining portion 41 is provided at the radial outer part of thecolumn portion 13 for preventing the taper roller 4 from falling out tothe radial outer side (refer to FIGS. 2 and 6).

In FIG. 12, the second roller retaining portions 42 are provided on thelarge-diameter annular portion 12 side, that is, on both sides in thecircumferential direction of each of the column portions 13. The secondroller retaining portion 42 is provided at the radial outer part of thecolumn portion 13 for preventing the taper roller 4 from falling out tothe radial outer side (refer to FIG. 2).

In addition, the first roller retaining portion 41 and the second rollerretaining portion 42 are discontinuous to each other, and are providedto be separated from each other in the column portion longitudinaldirection.

The first roller retaining portion 41 has a shape of a protruding beamwhich is a fixed end on the column portion 13 side and on thesmall-diameter annular portion 11 side, and is a free end on the tip endside in the extending direction which extends in the circumferentialdirection and in the column portion longitudinal direction. In otherwords, the first roller retaining portion 41 has a shape of a protrudingbeam (a shape of a cantilever beam) which is a fixed end beingintegrated with the column portion 13 at one end 43 in thecircumferential direction on the column portion 13 side, and is a freeend at another end 45 in the circumferential direction on the other endside in the column portion longitudinal direction while being a fixedend which is integrated with the small-diameter annular portion 11 atone end 44 in the column portion longitudinal direction on thesmall-diameter annular portion 11 side. Each of the first rollerretaining portions 41 is likely to be deformed since the first rollerretaining portions 41 have such a shape of a protruding beam, and inparticular, have a shape of which a tip portion side in the protrudingdirection is likely to be bent.

Although not being illustrated, in a case where the first rollerretaining portion 41 and the second roller retaining portion 42 arecontinuous to each other and the first roller retaining portion 41 isnot a free end on the other end side in the column portion longitudinaldirection, rigidity of the first roller retaining portion 41 increases,and the first roller retaining portion 41 is configured to be unlikelyto be deformed.

The second roller retaining portion 42 is provided on the large-diameterannular portion 12 side, and is provided to protrude in thecircumferential direction from the column portion 13. The second rollerretaining portion 42 is discontinuous to the large-diameter annularportion 12, and has a shape of a cantilever beam that can be deformedindependently from the large-diameter annular portion 12. In otherwords, the second roller retaining portion 42 is a fixed end which isintegrated with the column portion 13 at one end 47 in thecircumferential direction on the column portion 13 side, and is a freeend at the other end 48 in the circumferential direction.

Above, one pair of first roller retaining portions 41 and 41 is providedon both circumferential sides of one pocket 14 on the small-diameterannular portion 11 side, and a pocket width (dimension in thecircumferential direction of the pocket 14) on the small-diameterannular portion 11 side becomes smaller than a taper roller width(diameter of the taper roller 4 at corresponding positions) due to thefirst roller retaining portions 41 and 41.

Similar to this, one pair of second roller retaining portions 42 and 42is provided on both circumferential sides of one pocket 14 on thelarge-diameter annular portion 12 side, and a pocket width (dimension inthe circumferential direction of the pocket 14) on the large-diameterannular portion 12 side becomes smaller than a taper roller width(diameter of the taper roller 4 at corresponding positions) due to thesecond roller retaining portions 42 and 42.

Above, the cage 10 can hold the taper roller 4 by preventing the taperroller 4 in the pocket 14 from falling out to the radial outer side. Inaddition, attachment of the taper roller 4 to the pocket 14 can beperformed from the inner circumferential side.

As described above, in order to assemble the taper roller bearing 1,first, as illustrated in FIG. 13(A), in a state where the taper rollers4 are accommodated in each of the pockets 14 of the cage 10, the taperrollers 4 are allowed to approach the inner ring 2 from the axialdirection and assembled thereto. At this time, the taper roller 4 isprevented from falling out to the radial outer side by the rollerretaining portions 41 and 42, and the assembly becomes easy. Inaddition, when assembling the taper roller bearing 1, as illustrated inFIG. 13(B), it is necessary that a small-diameter side part 49 of thetaper roller 4 climbs over the small flange 5 of the inner ring 2, andit is necessary that the taper roller 4 (small-diameter side part 49) isdisplaced to the radial outer side, and deforms the first rollerretaining portion 41 on the radial outer side.

Here, as described above, as the first roller retaining portion 41 has ashape (in particular, a shape by which the tip portion side in theprotruding direction is likely to be bent) which is likely to bedeformed, the taper roller 4 can easily climb over the small flange 5pushing (elastically deforming) the first roller retaining portion 41,and the assembly becomes easy.

In the related art, since the column portion functions as a rollerretaining portion across the entire length, the rigidity is high, and ina case where the assembly is performed by a similar method, it isnecessary to elastically deform the column portion and thesmall-diameter annular portion. Therefore, the assembly is performed byusing a press in the related art. However, in the embodiment, since thefirst roller retaining portion 41 is easily deformed, the assembly canbe performed by a force (manually) of a worker without using a press.

Furthermore, as illustrated in FIG. 13(C), when the taper roller 4 andthe cage 10 are assembled to the inner ring 2, since the movement of thetaper roller 4 to the radial outer side is regulated by the cage 10 andthe axial movement is also not possible being hooked to the small flange5 and the large flange 6, disassembly becomes impossible. Therefore, forexample, even when the unit of the inner ring 2, the taper roller 4, andthe cage 10 is dropped to a floor or the like, it becomes possible toprevent the inner ring 2, the taper roller 4, and the cage 10 fromcoming apart.

In addition, although not being illustrated, by allowing the outer ring3 to approach to the unit of the inner ring 2, the taper roller 4, andthe cage 10 which are integrated with each other from the axialdirection, and by assembling the outer ring 3 to the unit, the taperroller bearing 1 is configured.

In addition, in the embodiment, the cage 10 includes the second rollerretaining portion 42 which is separated in the column portionlongitudinal direction other than the first roller retaining portion 41.Therefore, it is possible to reliably prevent the taper roller 4 fromfalling out from the pocket 14 by the first roller retaining portion 41and the second roller retaining portion 42. Furthermore, since the firstroller retaining portion 41 is separated from the second rollerretaining portion 42 in the column portion longitudinal direction, it ispossible to prevent the deformation of the first roller retainingportion 41 from being restricted by the second roller retaining portion42. In other words, it is possible to prevent characteristics that thedeformation of the first roller retaining portion 41 is easy fromdeteriorating.

FIG. 14 is a perspective view of the cage 10 and the taper roller 4. Asdescribed above, a part of the outer circumferential surface 11 a of thesmall-diameter annular portion 11 can slidably come into contact withthe inner circumferential surface 3 b of the outer ring 3 (end portion 3d). Therefore, a part of the outer circumferential surface 11 a of thesmall-diameter annular portion 11, a part of the radial outer surface ofthe column portion 13 (a part on the small-diameter annular portion 11side), and the radial outer surface of the first roller retainingportion 41 are included in the slide contact surface 40 which slidablycomes into contact with the inner circumferential surface 3 b of theouter ring 3, and the slide contact surface 40 can be positioned withrespect to the radial direction of the cage 10 together with the slidecontact surface 39 on the large-diameter annular portion 12 side.Accordingly, the cage 10 becomes the taper roller bearing 1 which isguided by the outer ring 3. In addition, the clearance (K1: refer toFIG. 3) formed between the outer circumferential surface 11 a (slidecontact surface 40) of the small-diameter annular portion 11 and theinner circumferential surface 3 b in the end portion 3 d of the outerring 3 becomes fine, and intrusion of the lubricating oil on the outsideof the bearing to the inside of the bearing becomes difficult. As aresult, as described above, it is possible to reduce rolling viscosityresistance and agitating resistance in the taper roller bearing 1.

In addition, the radial outer surface of the second roller retainingportion 42 configures the slide contact surface 39 which is slidable onthe inner circumferential surface 3 b of the outer ring 3, andaccordingly, the slide contact surface 39 can be positioned with respectto the radial direction of the cage 10 together with the slide contactsurface 40 on the small-diameter annular portion 11 side.

In addition, in the taper roller bearing 1, as described by using FIG.12, one pair of first roller retaining portions 41 and 41 is provided onboth sides in the circumferential direction of one pocket 14 on thesmall-diameter annular portion 11 side, and the pocket width on thesmall-diameter annular portion 11 side becomes smaller than the taperroller width by the first roller retaining portions 41 and 41. In otherwords, as illustrated in FIG. 14, the first roller retaining portion 41includes an arc surface portion 41 a which is continuous to the outercircumferential surface 11 a of the small-diameter annular portion 11and is provided along smooth arc surface on the radial outer side. Inaddition, a circumferential width (the pocket width) W of the pocket 14which is defined as a dimension between one pair of first rollerretaining portions 41 and 41 that are provided on both sides in thecircumferential direction of the pocket 14, becomes smaller than theminimum value (diameter of the small end surface 4 a) of the width inthe circumferential direction of the taper roller 4.

In this case, the lubricating oil which can intrude the fine clearanceK1 (refer to FIG. 3) formed between the outer circumferential surface 11a (slide contact surface 40) of the small-diameter annular portion 11and the end portion 3 d of the outer ring 3 flows to the other axialside along the inner circumferential surface 3 b of the outer ring 3,but a part thereof intrudes to the inside of the pocket 14 blocked bythe small end surface 4 a of the taper roller 4. However, as illustratedin FIG. 14, as the circumferential width W of the pocket 14 decreases,it is possible to suppress the intrusion of the lubricating oil to theinside of the pocket 14. As a result, it is possible to reduce rollingviscosity resistance and agitating resistance in the taper rollerbearing.

Furthermore, the lubricating oil which can intrude to the fine clearanceK1 and exists on the radial outer side of the column portion 13 flowsbackward to the small-diameter annular portion 11 side and further flowsto the radial outer side of the adjacent column portion 13 climbing overthe small-diameter side of the taper roller 4 according to the rotationof the taper roller 4. However, in the embodiment, since the firstroller retaining portion 41 includes the arc surface portion 41 a whichis continuous to the outer circumferential surface 11 a of thesmall-diameter annular portion 11 and is provided along the smooth arcsurface, on the radial outer side, it is possible to make it difficultfor the flow of the lubricating oil to be generated. In other words,since the surface which opposes the inner circumferential surface 3 b ofthe outer ring 3 having the fine clearance K1 widens being added by thearc surface portion 41 a, resistance of the flow of the lubricating oilincreases, and it is possible to suppress generation of the backwardflow described above.

[Regarding Taper Roller Bearing 1 and Split Mold]

Since the cage 10 is made of a resin, molding is performed by injectinga molten resin to a cavity of the mold and hardening the molten resin.In addition, the manufacturing of the cage 10 is performed by theinjection molding. In the embodiment, as illustrated in FIG. 15, thecage 10 has a configuration in which the molding is possible using ahalf-split mold 50 including a first mold 51 that moves to one sidealong a center line C2 of the cage 10 and a second mold 52 that moves tothe other side along the center line C2. In addition, the cavity formolding the cage 10 is formed between the first mold 51 and the secondmold 52, but an annular mold 53 which is externally fitted to the firstmold 51 and the second mold 52 is also provided in the mold 50.

In a state where the first mold 51 and the second mold 52 are relativelymoved along the center line C2 and are allowed to approach each other,and are further assembled on the inner side of the annular mold 53, themolten resin is injected into the cavity, cooled, and hardened. Inaddition, by relatively moving the first mold 51 and the second mold 52along the center line C2 and making the first mold 51 and the secondmold 52 separated from each other, the mold of the cage 10 which is amolded article is removed.

In this manner, in order to use the mold that configures the cavity asthe two-split molds (51 and 52), when the molds 51 and 52 are separatedand removed, it is necessary that the molded article is configured inwhich a so-called forced extraction is not generated, and the cage 10 ofthe embodiment is configured in this manner.

Specifically speaking, the cage 10 is configured of the small-diameterannular portion 11, the large-diameter annular portion 12, and theplurality of column portions 13, and the surface of the entire cageincluding the small-diameter annular portion 11, the large-diameterannular portion 12, and all of the column portions 13, is configured byaggregating a surface viewed from one axial side (refer to FIG. 16) anda surface viewed from the other axial side (refer to FIG. 17). In otherwords, each surface of the cage 10 is configured to be necessarily seenfrom one axial side or the other axial side. FIG. 16 is a view (frontview) of a part of the cage 10 viewed from one axial side parallel tothe center line C2 of the cage 10, and FIG. 17 is a view (rear view) ofa part of the cage 10 viewed from the other axial side parallel to thecenter line C2 of the cage 10.

The next surface is included in the surface of the entire cage.

In the small-diameter annular portion 11, the outer circumferentialsurface 11 a, the inner circumferential surface 11 b, the axial innersurface 11 c, and an axial outer surface 11 d are included. In thelarge-diameter annular portion 12, an outer circumferential surface 12b, the inner circumferential surface 12 a, the axial inner surface 12 c,and an axial outer surface 12 d are included.

In the column portion 13, the radial inner surface 17, a radial outersurface 37, and the side surfaces 13 c on both sides are included. Inthe first roller retaining portion 41 in the column portion 13, theslide contact surface 40 on the small-diameter annular portion 11 sideand a rear surface 40 a of the slide contact surface 40 are included. Inaddition, in the second roller retaining portion 42, the slide contactsurface 39 on the large-diameter annular portion 12 side, a rear surface39 a of the slide contact surface 39, a surface 40 b on one axial side,and a surface 40 c on the other axial side.

Here, as illustrated in FIG. 16, when the cage 10 is viewed from oneaxial side, the outer circumferential surface 11 a and the axial outersurface 11 d of the small-diameter annular portion 11 are viewed, theaxial inner surface 12 c of the large-diameter annular portion 12 isviewed, and the radial outer surface 37 of the column portion 13 isviewed. Furthermore, the slide contact surface 40 of the first rollerretaining portion 41 is viewed, and the surface 40 b and the slidecontact surface 39 on one axial side of the second roller retainingportion 42 is viewed. Since the inner circumferential surface 12 a ofthe large-diameter annular portion 12 is formed on the circular surfaceof which the diameter is greater than that of the outer circumferentialsurface 11 a of the small-diameter annular portion 11, the entire axialinner surface 12 c is deservedly viewed.

Meanwhile, as illustrated in FIG. 17, when the cage 10 is viewed fromthe other axial side, the inner circumferential surface 11 b and theaxial inner surface 11 c of the small-diameter annular portion 11 areviewed, the outer circumferential surface 12 b, the innercircumferential surface 12 a, and the axial outer surface 12 d of thelarge-diameter annular portion 12 are viewed, and the radial innersurface 17 of the column portion 13 and the side surfaces 13 c on bothsides are viewed. Furthermore, when the rear surface 40 a of the firstroller retaining portion 41 is viewed, the rear surface 39 a of thesecond roller retaining portion 42 and the surface 40 c on the otheraxial side are viewed.

In FIG. 17, in particular, the groove 18 is formed on the radial innersurface 17 of the column portion 13, and all of the surfaces of thegroove 18 are viewed from one axial side. In other words, since theradial inner surface 17 of the column portion 13 has a shape along thetaper surface of which the diameter increases as approaching the otherside from one axial side, the radial inner surface 17 is viewed from theother axial side. In addition, on the radial inner surface 17, thegroove 18 which extends along the longitudinal direction of the columnportion 13 and is open on the other axial side is formed, and the endportion (groove final end) 18 d of the groove 18 is also viewed from theother axial side. In other words, in the embodiment, as described above,since the groove 18 has a shallow part 18 e (refer to FIGS. 7 and 8) andthe groove depth becomes zero at the groove final end (end portion 18d), the groove 18 is open on the other axial side. Therefore, the groove18 is completely viewed from the other axial side.

In a case where the groove 18 is not open in the end portion on theother axial side, the inner surface of the part at which the opening isclosed is not included in either the surface viewed from one axial sideor the surface viewed from the other axial side, the axial movement ofone mold (second mold 52) of the first mold 51 and the second mold 52 isinhibited by the part at which the opening is not closed, and themanufacturing of the cage 10 using the half-split mold becomesimpossible.

However, according to the configuration of the groove 18 according tothe embodiment, each portion of the entire groove 18 is viewed from theother axial side, and the manufacturing of the cage using the half-splitmold becomes possible.

In addition, as described above (refer to FIG. 5), the radial innersurface 17 of the column portion 13 is provided along the second virtualtaper surface J2 in the vicinity of (or being matched) the first virtualtaper surface J1 including the center line C1 of the plurality of taperrollers 4 held by the pocket 14 across the entire length in thelongitudinal direction of the column portion 13. Accordingly, when thetaper roller bearing 1 rotates, the radial inner surface 17 of thecolumn portion 13 can scrape the lubricating oil attached to the outercircumferential surface of the taper roller 4 across the entire lengthin the longitudinal direction of the column portion 13. Accordingly, itis possible to reduce rolling viscosity resistance and agitatingresistance.

However, as illustrated in FIG. 18, in a case where the column portion13 is configured to be long in the radial direction to a position atwhich the radial inner surface 17 of the column portion 13 is close tothe inner ring, in order to scrape the lubricating oil attached to theouter circumferential surface of the taper roller by the radial innersurface 17 of the column portion 13, the radial inner surface 17 issupposed to have a shape which widens in the circumferential directionas illustrated in FIG. 18. However, in this case (refer to FIG. 18), ata part having a widening shape, a surface which is not included ineither the surface viewed from one axial side or the surface viewed fromthe other axial side exists. In other words, in the embodiment (FIG.17), the side surface 13 c of the column portion 13 viewed from theother axial side is not viewed from the other axial side in the exampleof FIG. 18 (further, also not viewed from one axial side), and themanufacturing of the cage 10 illustrated in FIG. 18 is impossible usingthe half-split mold which moves to approach and be separated in theaxial direction.

Here, as described in the embodiment, as the radial inner surface 17 ofthe column portion 13 is provided along the second virtual taper surfaceJ2, it is possible to manufacture the cage 10 made of a resin using thehalf-split molds (51 and 52) while having a function of scraping thelubricating oil of the taper roller 4.

In addition, as described above, in order to flow the lubricating oil inthe vicinity of the inner circumferential surface 3 b of the outer ring3 between the pockets 14 and 14 adjacent to each other and weakenagitating resistance of the lubricating oil, the recess portion 33 isformed on the radial outer side of the column portion 13 (refer to FIG.5). Here, in the recess portion 33, the depth of the end 33 a on oneaxial side is zero and the bottom surface of the recess portion 33 has ashape of an inclined surface that is inclined as approaching the radialouter side toward the other axial side.

Accordingly, even when the recess portion 33 is formed on the radialouter side of the column portion 13, the molding using the half-splitmolds (51 and 52) is maintained. In other words, by configuring therecess portion 33 in this manner, the entire recess portion 33 becomes asurface viewed from one axial side (refer to FIG. 16). Therefore, in therecess portion 33, the first mold 51 can move to one axial side withoutforced extraction.

Above, as the surface of the entire cage is configured by aggregatingthe surface viewed from one axial side (refer to FIG. 16) and thesurface viewed from the other axial side (refer to FIG. 17), it ispossible to manufacture the cage 10 made of a resin using the half-splitmolds that configure the cavity by the first mold 51 which moves to oneaxial side and the second mold 52 which moves to the other axial side.As a result, mass productivity of the cage 10 is improved.

In addition, although not being illustrated, the cage 10 of theembodiment illustrated in FIG. 2 may also use a third mold which movesin the radial direction for forming the pocket other than the first andthe second molds which relatively move in the axial direction. However,in this case, a split surface of the mold increases, management ofdimension accuracy of the cage become difficult, and there is apossibility that accuracy of the cage 10 deteriorates. In addition, lifeof the mold is shortened. However, according to the half-split mold 50illustrated in FIG. 15, the split surface decreases, it becomes possibleto manufacture the cage 10 with high accuracy, and it is possible toprevent deterioration of life of the mold.

The embodiments disclosed above are merely examples in all aspects andare not limited thereto. In other words, the taper roller bearing of thepresent invention may be another aspect within the range of the presentinvention not being limited to the aspects illustrated in the drawings.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to scrape lubricatingoil attached to an outer circumferential surface of the taper roller bya radial inner surface of a column portion, and to reduce rollingviscosity resistance and agitating resistance. Accordingly, it ispossible to reduce energy loss in an apparatus in which the taper rollerbearing is used.

REFERENCE SIGNS LIST

-   -   1: TAPER ROLLER BEARING    -   2: INNER RING    -   3: OUTER RING    -   4: TAPER ROLLER    -   5: SMALL FLANGE    -   5 a: OUTER CIRCUMFERENTIAL SURFACE    -   6: LARGE FLANGE    -   6 a: OUTER CIRCUMFERENTIAL SURFACE    -   8: SHAFT    -   9: CIRCULAR PORTION    -   10: CAGE    -   11: SMALL-DIAMETER ANNULAR PORTION    -   11 a: OUTER CIRCUMFERENTIAL SURFACE    -   11 b: INNER CIRCUMFERENTIAL SURFACE    -   12: LARGE-DIAMETER ANNULAR PORTION    -   12 a: INNER CIRCUMFERENTIAL SURFACE    -   12 c: AXIAL INNER SURFACE    -   13: COLUMN PORTION    -   14: POCKET    -   15: CUT-OUT PORTION    -   16: CAVITY PORTION    -   16 a: RADIAL OUTER END PORTION    -   17: RADIAL INNER SURFACE    -   18: GROOVE    -   18 e: SHALLOW PART    -   21: FIRST INNER CIRCUMFERENTIAL SURFACE PORTION    -   22: SECOND INNER CIRCUMFERENTIAL SURFACE PORTION    -   24: FIRST OUTER CIRCUMFERENTIAL SURFACE PORTION    -   25: SECOND OUTER CIRCUMFERENTIAL SURFACE PORTION    -   26: FIRST INNER CIRCUMFERENTIAL SURFACE PORTION    -   27: SECOND INNER CIRCUMFERENTIAL SURFACE PORTION    -   29: FIRST OUTER CIRCUMFERENTIAL SURFACE PORTION    -   30: SECOND OUTER CIRCUMFERENTIAL SURFACE PORTION    -   33: RECESS PORTION    -   33 a: END    -   33 b: BOTTOM SURFACE    -   40: SLIDE CONTACT SURFACE    -   41: FIRST ROLLER RETAINING PORTION    -   41 a: ARC SURFACE PORTION    -   42: SECOND ROLLER RETAINING PORTION    -   A1: ANNULAR OPENING PORTION    -   A2: ANNULAR OPENING PORTION    -   C1: CENTER LINE    -   J1: FIRST VIRTUAL TAPER SURFACE    -   J2: SECOND VIRTUAL TAPER SURFACE    -   J3: VIRTUAL EXTENDING LINE    -   K0: RADIAL CLEARANCE    -   K2-1: FINE CLEARANCE    -   K2-2: FINE CLEARANCE    -   K3-1: FINE CLEARANCE    -   K3-2: FINE CLEARANCE    -   K10: RADIAL CLEARANCE

The invention claimed is:
 1. A taper roller bearing comprising: an innerring which includes a small flange that is positioned on one side in anaxial direction and protrudes to an outer side in a radial direction,and a large flange that is positioned on the other side in the axialdirection and protrudes to the outer side in the radial direction; anouter ring which is positioned on the outer side in the radial directionof the inner ring; a plurality of taper rollers which are positionedbetween the inner ring and the outer ring; and an annular cage whichholds the plurality of taper rollers at an interval in thecircumferential direction, wherein the cage includes a small-diameterannular portion which is positioned on the one side, a large-diameterannular portion which is positioned on the other side, and a pluralityof column portions which link the small-diameter annular portion and thelarge-diameter annular portion to each other, a cylindrical innersurface of the small-diameter annular portion opposes an outercircumferential surface of the small flange in the radial direction at aposition axially outward of the grooves, and an annular clearance isformed therebetween to limit inflow of lubricating oil, an inner surfacein the radial direction of each of the column portions is positionedalong a second virtual taper surface which is in the vicinity of a firstvirtual taper surface including center lines of the plurality of taperrollers or which fits the first virtual taper surface, across an entirelength in a longitudinal direction of the column portions, and groovesare formed on the inner surface in the radial direction of the columnportions, each of the grooves extending along the longitudinal directionof each of the column portions and being open on the other side andclosed on the one side.
 2. The taper roller bearing according to claim1, wherein an extending virtual line which extends from an end portionon an opening side of a bottom portion of each of the grooves intersectswith a flange surface on the inner side in the axial direction of thelarge flange.
 3. The taper roller bearing according to claim 1, whereina diameter of the second virtual taper surface is slightly smaller thana diameter of the first virtual taper surface.
 4. The taper rollerbearing according to claim 1, wherein each of the grooves has a partwhich becomes more shallow as approaching an end of each of the grooveson the other side.
 5. The taper roller bearing according to claim 1,wherein the cage includes a slide contact surface which is arranged toslidably contact with an inner circumferential surface of the outer ringso as to position with respect to the radial direction of the cage.